This invention relates to cameras having control system for coordinating the various portions of the exposure control apparatus including an electric generator incorporated in the camera.
It is known to provide a camera having an electronic shutter supplied with electrical power from an electric generator, as, for example, in Japanese Laid-Open Patent No. Sho 52-34723. With the camera having broadened capabilities, however, as electrical power must be supplied not only to the electromagnetic actuator and timing circuit controlling the period of actuation of the shutter, but also to the amplifier circuit for the light sensor, exposure value computer, and the display circuit for displaying the exposure value and the various warning signals, and, in the dual priority cameras, further to the complicated coordinating control for the diaphragm and shutter mechanisms, the amount of electrical energy consumed at a time by these portions of the camera tends to exceed the level available from the small generator.
On the other hand, the battery-fed camera often prevents the photographer from making an exposure even in the manual mode as the shutter is electrically operated with power supply from the battery. Where no new battery is obtainable to replace the old one, the multi-purpose camera becomes incapable of performing even the most fundamental function of a simple basic camera.
To obviate this defect the use of a mechanical governor in addition to the timing circuit in controlling the shutter at a region of shorter exposure times has been attempted. The use of such mechanical governor, however, necessitates a relatively large space for the governor and a selection control mechanism to occupy. Further, this shutter arrangement is very disadvantageous in providing both of the shutter and diaphragm preselection automatic exposure ranges. Another attempt has been made to permit the shutter to take an exposure through a control mechanism but the exposure time is limited to only one value when the battery is no longer useful. This provision can not be said to be satisfactory.
Accordingly, it is an object of the present invention to provide a camera having an automatic exposure control apparatus with an electronic shutter cooperating in selective manner with a battery and an electric generator incorporated in the camera. When the actual voltage of the battery is above a satisfactory operating level, the electronic shutter is controlled in accordance with either the output of the exposure value computer or the manually preset value of exposure time, while being supplied with electrical power from the battery.
Another object of the present invention is to make an exposure in the manual mode by supplying electrical power to at least the camera release actuating circuit and shutter control circuit from the generator while preserving a large proportion of the range of exposure times available on the shutter dial, when the full electrical energy of the battery is used up and where no new battery is obtainable at hand.
To achieve this, according to one embodiment of the invention applied to the camera of the shutter preselection automatic exposure control type, the film winding mechanism is automatically brought into driving connection with a spring-powered gear for later application of mechanical energy to the generator in response to removal of the battery from the chamber within the camera housing, provided that the shutter dial is operated to select a desired shutter speed from a region of faster values than 1/8 second, for example. During the first stroke of the shutter button, the generator is driven by the spring-powered gear to produce electrical energy which is stored on three capacitors. Upon the second stroke, a magnetic winding is energized to release the shutter from the closed position and a timing capacitor starts to be charged with power supplied from the respective capacitors. At the termination of duration of the exposure time, the third capacitor is suddenly discharged through a magnetic winding to close the shutter again.
The present invention will be better understood when reference is had to the accompanying drawings in which: